domain aliases

Now I want it to automatically have admin@mydomain.com to go to this mailbox, but I don't want to have to set it for each and every user. Is there a way to set multiple domain aliases so that I don't have to specify it on each user? I'm not sure what to search for in the wiki, I see the split domain setup but I don't want some users to receive mail, I want to do a hard swap to the new server.

So for now I have just added the entries I need, but when I try to manually test I cannot send a message! I am telnetting directly to the new zimbra server on port 25 from the old server across the internet.

The old server is still live, so I cannot just swap DNS/MX and such and hope it works.

But the catch-all doesn't seem to work when I telnet, yet it is at least partially working because it works from the 3rd party mail provider. When I try to do it via telnet it returns:
550 5.1.1 : Recipient address rejected: mydomain.com

A catchall email address (expect for the migration period) is never a good idea, it's a spammers dream target.

The A record has always been there, the MX records won't come until I do the move, BUT the server thinks it has them now. The server is running DNS on itself now, and if I dig the domain it does show the new IP of the server.

A Split domain setup isn't going to happen, there are only 5 users and everything else is aliases to those 5 users.

The old server processes over 100,000 spams a day to the legitimate addresses, the few extras from the catch-all don't do much. I expect spamassassin to work as it does now on the old server (it gets over 99% of them).

I don't understand why when I manually telnet to the box from the old server (different datacenter) it doesn't work, but if I send to the catch-all from a 3rd party mailserver to the zimbra.mydomain.com subdomain it does work!